全文获取类型
收费全文 | 537148篇 |
免费 | 28281篇 |
国内免费 | 517篇 |
专业分类
耳鼻咽喉 | 6769篇 |
儿科学 | 17064篇 |
妇产科学 | 12759篇 |
基础医学 | 93429篇 |
口腔科学 | 12629篇 |
临床医学 | 49131篇 |
内科学 | 97065篇 |
皮肤病学 | 11954篇 |
神经病学 | 34523篇 |
特种医学 | 20041篇 |
外国民族医学 | 53篇 |
外科学 | 79270篇 |
综合类 | 7886篇 |
现状与发展 | 2篇 |
一般理论 | 113篇 |
预防医学 | 39172篇 |
眼科学 | 12038篇 |
药学 | 41806篇 |
1篇 | |
中国医学 | 1127篇 |
肿瘤学 | 29114篇 |
出版年
2021年 | 3993篇 |
2019年 | 4005篇 |
2018年 | 5855篇 |
2017年 | 4222篇 |
2016年 | 4984篇 |
2015年 | 5493篇 |
2014年 | 7312篇 |
2013年 | 10775篇 |
2012年 | 15986篇 |
2011年 | 17814篇 |
2010年 | 10219篇 |
2009年 | 9085篇 |
2008年 | 16152篇 |
2007年 | 17898篇 |
2006年 | 17408篇 |
2005年 | 16727篇 |
2004年 | 16293篇 |
2003年 | 15677篇 |
2002年 | 15142篇 |
2001年 | 22572篇 |
2000年 | 23139篇 |
1999年 | 19067篇 |
1998年 | 5355篇 |
1997年 | 4446篇 |
1996年 | 4461篇 |
1995年 | 4182篇 |
1992年 | 14509篇 |
1991年 | 15893篇 |
1990年 | 16012篇 |
1989年 | 15685篇 |
1988年 | 14373篇 |
1987年 | 14255篇 |
1986年 | 13244篇 |
1985年 | 12746篇 |
1984年 | 9451篇 |
1983年 | 8057篇 |
1982年 | 4218篇 |
1979年 | 8966篇 |
1978年 | 6429篇 |
1977年 | 5184篇 |
1976年 | 5550篇 |
1975年 | 6650篇 |
1974年 | 7455篇 |
1973年 | 7186篇 |
1972年 | 6626篇 |
1971年 | 6339篇 |
1970年 | 5921篇 |
1969年 | 5499篇 |
1968年 | 5178篇 |
1967年 | 4637篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
David A. Hughes Graham C. Smith Joyce E. Davidson Anna V. Murphy T. James Beattie 《Pediatric nephrology (Berlin, Germany)》1996,10(4):445-447
. Neutrophil-mediated tissue damage has been implicated in the pathogenesis of diarrhoea-associated haemolytic uraemic syndrome
(D+ HUS). This study evaluates priming and activation of the neutrophil oxidative burst in D+ HUS using chemiluminescent techniques.
Peripheral blood neutrophils from 11 children with acute D+ HUS were examined. No difference was found in the oxidative burst
of neutrophils from patients and controls. Serum elastase levels were measured in 8 patients and found to be significantly
elevated. Although elastase results suggest neutrophil activation, chemiluminescence studies do not confirm this in the peripheral
blood neutrophil. This does not support a significant role for circulating agents in priming and activating the peripheral
blood neutrophil.
Received August 17, 1995; received in revised form and accepted November 27, 1995 相似文献
53.
Segregation analysis of leprosy in families of northern Thailand 总被引:4,自引:0,他引:4
Sixty-three families with multiple instances of leprosy were identified through a major leprosy treatment center in northern Thailand. Complex segregation analyses for single major genes or polygenic inheritance were performed using the maximum-likelihood routine POINTER to determine the most likely etiologic model of genetic susceptibility. Liability differences between men and women were considered in these models. When individuals were considered to be affected because they had any form of leprosy, a generalized major gene model with nearly dominant parameters on the liability scale, but additive penetrances, was found to be the most likely. When only those individuals who had tuberculoid forms of leprosy were considered to be affected, a recessive model was found to be the most likely; however, the discrimination between various models was poor. Further analyses are necessary to delineate genetic mechanisms to explain these apparently divergent results. In particular, methods of testing two locus models should be considered. 相似文献
54.
Reevaluation of procarbazine for the treatment of recurrent malignant central nervous system tumors 总被引:1,自引:0,他引:1
Ninety-nine patients with primary recurrent malignant tumors of the central nervous system were treated with procarbazine as a single agent. Procarbazine was not given as a specified protocol, but for patients who were ineligible or refused other protocols. All patients had been treated previously with radiotherapy and 96 patients had also received previous chemotherapy. Twenty-five patients were treated at the first progression of their tumor, 47 were treated at the second progression, and 27 were treated at the third progression of their tumor. For the aggregate, the response plus stabilization rate was 27% for glioblastoma multiforme with median time to tumor progression of 30 weeks, and 28% for other anaplastic gliomas with a median time to tumor progression of 49 weeks. With respect to the percent of patients who responded or stabilized to treatment, these results are inferior to those reported previously for patients treated with procarbazine at recurrence. With respect to duration of response and stabilization, the data are comparable. 相似文献
55.
J. Viac C. Goujon L. Misery V. Staniek M. Faure D. Schmitt A. Claudy 《Photodermatology, photoimmunology & photomedicine》1997,13(3):103-108
Ultraviolet radiation B (UVB) on the skin induces erythema, inflammation and modifications of the immune system. These changes have been reported after excessive short-term or long-term exposure to broad spectrum UVB. In this study, we examined the effects of local repetitive UVB irradiation of 311 nm wavelength on the skin of seven young volunteers. Skin biopsies were taken before and after UVB irradiation, and we immunohistochemically analyzed the expression of CD1a and HLA-DR antigens of Langerhans cells (LC), the possible infiltration of dermis/epidermis by CD11b macrophages, the modifications or the induction of intercellular adhesion molecule-1 (ICAM-1), E-selectin and vascular cell adhesion molecule-1 (VCAM-1) involved in the binding of leukocytes to the endothelial surface and the development of perivascular infiltrates of LFA-1+ mononuclear cells. We also determined the expression of substance P receptors (SPR) using biotinylated substance P (SPB). Exposure of UVB 311 nm induced a drastic reduction of CD1a+ cells and a moderate increase of HLA-DR+ dendritic cells in the epidermis without infiltration by CD11b macrophages. An increase of the binding of SPB to upper layer epidermal cells was noted in five of seven biopsies. In the dermis, vessel-associated ICAM-1 expression increased and an induction of E-selectin occurred on nearly 20 to 40% of endothelial cells, but VCAM-1 expression remained undetectable. The percentage of LFA-1+ cells did not change significantly after irradiation. These observations may be compatible with a selective role of UVB 311 nm on the skin immune response. 相似文献
56.
R. LIBERMAN E.C. COMBE† V. PIDDOCK† C. PAWSON D.C. WATTS† 《Journal of oral rehabilitation》1995,22(6):445-449
SUMMARY Current standard specifications for the laboratory evaluation of denture base materials require subjective assessment of colour stability. This study evaluates a new objective measurement technique for translucent denture base materials, by comparing quantitative data with the results obtained from a standard subjective method. Preliminary work on three representative commercial acrylic materials resulted in the selection of a white background for the quantification of colour change of these translucent materials. One half of each sample was exposed to artificial sunlight for 24 h.
The colour of both exposed and unexposed resin was measured on the CIE L*a*b* scale using a photoelectric colorimeter. Significant changes in the b* and E* values (P < 0.001) were observed following light exposure. Objective data for a wide range of commercial materials were compared with the results of a subjective evaluation and it was shown that a change in b* of 1.5 units was discernable subjectively by eye for 100% of the cases. It is suggested that this method and limit value could form the basis of a new objective colour change specification for polymeric dental materials. 相似文献
The colour of both exposed and unexposed resin was measured on the CIE L*a*b* scale using a photoelectric colorimeter. Significant changes in the b* and E* values (P < 0.001) were observed following light exposure. Objective data for a wide range of commercial materials were compared with the results of a subjective evaluation and it was shown that a change in b* of 1.5 units was discernable subjectively by eye for 100% of the cases. It is suggested that this method and limit value could form the basis of a new objective colour change specification for polymeric dental materials. 相似文献
57.
T F Kruger J P Van der Merwe H J Odendaal F S Stander G M Grobler V A Hulme E L Erasmus K Coetzee M L Windt Y Swart 《Suid-Afrikaanse tydskrif vir geneeskunde》1990,77(12):634-636
The results of the in vitro fertilisation programme at Tygerberg Hospital for the period April 1983 to January 1988 are presented. Of the 1117 laparoscopies performed, 825 patients reached the transfer stage. A live-birth rate of 9.3% was achieved. The pregnancy rate after transfer of 4 embryos was 25.9% compared with 15.4% after 2 embryos and 10.8% after 3 embryos (P = less than 0.0001). The multiple pregnancy rate was 2.8% in the group receiving 2 embryos and 11.7% and 10.4% in those receiving 3 and 4 embryos, respectively. Of the 77 successful pregnancies (90 babies), 1 baby died at 34 weeks' gestation as the result of abruptio placentae due to preeclampsia and 1 cot death occurred. The only congenital abnormality encountered was a cleft palate. 相似文献
58.
V K Kudriashov V A Semenchenia 《Klinichna khirurhiia / Ministerstvo okhorony zdorov'ia Ukra?ny, Naukove tovarystvo khirurhiv Ukra?ny》1990,(5):4-5
On the basis of the experience with treatment of more than 500 patients with sigmoid and rectal cancer, the informative value of the instrumental methods of investigation used for more precise definition of a stage of the disease is analysed. A scheme for rational examination of the patients is suggested. 相似文献
59.
T. M. Skerry M.D. M.R.C.V.S. R. Suswillo A. J. El Haj N. N. Ali R. A. Dodds L. E. Lanyon 《Calcified tissue international》1990,46(5):318-326
Summary Previous studies of Alcian blue-induced birefringence in adult avian cortical bone showed that a short period of intermittent
loading rapidly produces an increased level of orientation of proteoglycans within the bone tissue. In the absence of further
loading, this persists for over 24 hours. We have proposed that this phenomenon could provide a means for “capturing” the
effects of transient strains, and so provide a persistent, constantly updated strain-related influence on osteocyte populations
related to the bones' averaged recent strain history, in effect, a “strain memory” in bone tissue. In our present study, we
use the Alcian blue-induced birefringence technique to demonstrate that proteoglycan orientation also occurs after intermittent
loading of both cortical and cancellous mammalian bonein vivo andin vitro. We also show that the change in birefringence is proportional to the magnitude of the applied strain, and that the reorientation
occurs rapidly, reaching a maximal value after only 50 loading cycles. Examination of electron micrographs of bone tissue
after staining with cupromeronic blue allows direct visualization and quantification of the change in proteoglycan orientation
produced by loading. This shows that intermittent loading is associated with a realignment of the proteoglycan protein cores,
bringing them some 5 degrees closer to the direction of collagen fibrils in the bone matrix. 相似文献
60.